1. Field of the Invention
The present invention relates to a method of installing a window member in an infrared detector, for example a method of installing an interference filter in a pyroelectric detector, and in particular to a method of installing a window member provided with at least an electrically conductive material layer over an infrared incident opening extending through a can. The can is provided with a sensing element therein and the infrared incident opening and is formed of an electrically conductive material. The present invention also relates to the manufacture of an infrared detector provided with said window member mounted thereon.
2. Description of the Prior Art
In the prior infrared detector a can, provided with a sensing element therein and an infrared incident opening, is formed of an electrically conductive material (metal) but a window member such as an interference filter (transmitting an infrared light within the specific wave length range only) or a lens fixedly mounted over the infrared incident opening of the can are usually formed of an electrically nonconductive (insulating) material such as glass, so that problems have occurred in that shielding of such an electrically nonconductive window member can not be achieved and noise due to a disturbance such as an electromagnetic wave is generated.
So, for example in the case where an interference filter is used as the window member, as shown in FIG. 7, the window member has been made electrically conductive by forming interference filter layers b, b (usually formed in multi-layers by vacuum evaporation with electrically nonconductive materials) on the surface of a substrate layer "a" formed of a silicon (Si) smmiconductor, a germanium (Ge) semiconductor or the like. In the installment of the window member over the infrared incident opening of the can, as shown in for example FIG. 8, almost the entire circumferential edge surface of the window member c is adhered to the circumferential surface around the infrared incident opening e by means of electrically conductive adhesives f such as silver (Ag) paste to electrically and integrally connect the window member c with the can d, thereby forming a shield for the window member c, the can d and the connection therebetween, in short the whole infrared detector. However, in this case, since the adherence is carried out by means of only the electrically conductive adhesive f, there has been problems related to the strength of the adhered portions and to the durability.
Under these circumstances, in order to secure a shield so as to have sufficient strength and durability, the following method of installing a window member in an infrared detector has been practically used recently.
As shown at first in FIG. 9(A), the window member c adapted to have at least the electrically conductive material layer "a", as above described, is firmly adhered to the circumferential surface around the infrared incident opening e of the can d by means of epoxy resin and phenol resin electrically nonconductive adhesives g, which are said to have high adhesive strength, and to be waterproof and corrosion resistant, extending between the circumferential surface around the infrared incident opening e of the can d to a portion of the circumferential edge surface of the window member c so that at least the upper half of the circumferential edge surface of the electrically conductive material layer "a" is exposed. Then, as shown in FIG. 9(B), the electrically conductive adhesives f are applied so that said exposed upper half of the circumferential edge surface of the window member c is connected with an exposed end surface of the can d arranged therearound.
However, with the conventional method as shown in FIGS. 9(A), 9(B), since the adhesive applying process and drying process for drying the applied adhesives are performed twice each, productivity in the manufacturing of the detectors is low. Furthermore, in the process of applying electrically conductive adhesives f as shown in FIG. 9(B), fluctuation of the painting area and painted condition due to the manual operation is liable to occur, thereby leading to an incomplete shield and low yield of the products.